Fire-damp proof time fuse



May 3, 1932. E. KAR'oLLUs FIRE DAMP PROOF TIME FUSE Filed Sept. 29, 1930/N yeN fak Patented May 3, 1932 l stares FIRE-Dm PROF TME FUSEApplication ned september as, issu, sel-rei Ne. `islaam, ena Vin ansa-iaseptember pao, 1929.

This invention relates to a time fuse consisting in the known manner ofan electric glow fuse and a detonating cap. A retardation ordelay-action fuse contained in a special shell is inserted between theglow us'e,

and the detonating cap.

Gases are formedduring the ignition of the said fuse. These gases mustbe quickly dis charged, otherwise the shells containing the fuse wouldburst. A pointed dame is produced which immediately ignites the blastingcharge whereby the action f the time fuse, which consists in retardingthe ignition of the blasting charge, will be annulled.

However, the chief drawback of the formation of the said pointed ameresides in the fact that this llame is adapted to ignite fire damp.

A large number of arrangements or systems have become known which havefor their-object to quickly expand the gases formed during the lgnitionof the fuse and to cool them during the expansion so that apointed flamecan no longer be produced.

For this purpose, .porous material (filters) of non-infiammable matterin the form of plugs or -illers are provided in the path where the gasesareexpanded.

Practical experience has shown that it is not immaterial where theseporous materials (filters) are provided and in which direction the gasesare led. The filter materials must present only slight resistance to theadvance- Y ment of the gases. The filter materials must be so shaped andarranged that they cannot be compressed by the gas pressure to such anextent that they form an obstruction for the passage of thegases orclose the perforations o the fuse.

The openings of the `fuse,thro ugh which the gases escape into the borehole chamber, must be provided in such places of the fuse so that theycannot be covered externally.

All time fuses have the last drawback, wherein the openings are directedin the bore hole chamber on the obstruction side. The drawback thatparts of the filter material are forced internally against the outletopenings into the bore hole chamber and partial-n ly close same is to befound in most of those arrangements or systems wherein thesaid outletopenings4 are closed or protection against moisture or impuritiesexternally. Theinner pressure must increase until the plug or the likeis forced away or burnt.A The p ath for the gases is vthen suddenlyopened and the gases entrain parts of the filter material into theopening which is again closed. This process fr uently causes a burstingof the shell of these and the formation of a pointed flame.

These drawbacks" are obviated by the present invention by the followingarrangement or system.

Figure 1 shows a longitudinal sectional view of the invention.

Figure 2 shows a longitudinal sectional view of a modification of Fig.1, showing the ribs 11.

Figure 3 shows a cross sectional view thru the r1b section 11 of Fig. 2.

' The shell 4 Figure 1) contains in its upper part the e ectricallyignitable composition 1, below which there is a plug 12 com-` posed ofglass, slag, or asbestos wool and provided with a central bore 13wherein a tube 14 is inserted which does not extend to the endsv of thebore. During the ignition, the pointed llame coming from the electricfuse may freely. strike through the said tube Vand reach the retardationfuse 5 which is provided in the retarder 2. The retarder 2 is surroundedby the shell 8 which has a ange 10. .The shell 4 is mounted on the shell8. The shell 8 is of such dimensions that a space is left betweenit andthe shell 4. The

shells are fixed by a center-mark 6 so that the plug 12 of the shell 4firmly bears against the retardation fuse 5 and a rigid connectionv isformed between 4 and 8.

The end of the shell 8 directed toward the detonating cap 3 is slightlyconical-shaped so that the shell 7 of the detonating cap 3 --bearstightly on the said conical part of the shell 8 and the shell 8 cannotpass to thel composition of the cap.

According to the constructional form shown in Figures 2 and 3, the shell8 has longitudinal ribs 11 so far as it is inserted in the shell 4.

It is advisable to provide the shell 4, on its lower end opposite theflange 10 with notches or the like.

The fuse operates as follows:

As soon as the composition 1 of the electric fuse is ignited, thepointed flame thereof strikes through the tube 13 so the retardationfuse 5 which burns and ignites the composition of the detonating cap 3.

The excessive gases can immediately pass from the electric fuse 1, thenabove and below the tube 14 and from the retardation fuse 5 into theplug 12 without any obstruction; the gases are cooled therein and canfreely pass to the chamber between shell 4 and shell 8 whence they issuepast the edge 9 of the flange 10 into the bore hole chamber. This partof the bore hole chamber is always uncovered and a free exit of thegases is therefore also possible. It is possible by this arrangement toprevent a bursting of the shell and the formation of a pointed flame.

According to the present invention, it is possible to obtain a uniform,vfrictionless degassing free from a pointed flame in the space alwaysremaining free between composition and charge so that the duration ofvcombustion of a time fuse is maintained up to 116 part of a second andnot only a premature eXplosion of the blasting charge' is avoided butalso the security of the fire-damp is increased.

What I claim is:

Fire-damp proof time-fuse with a filter layer preventing the formationof a pointed flame, characterized in that the filter-plug made ofnon-inflammable fibrin in the known manner is arranged between theelectrically ignitable composition and the retarder and is provided withan axial bore, into which a tube is inserted but which does not extendto the ends of the bore in order to lead the pointed flame from theglow-fuse to the retarder.

In testimony whereof I affix my signature.

. EDMUND KAROLLUS.

